Method and apparatus for supporting multiple connections over different types of access in 3GPP systems

ABSTRACT

A method and apparatus for routing packets from a home agent to a user equipment through a first access network and a second access network. The method includes sending a first binding update message from the user equipment over the first access network to create a first binding cache entry at the home agent. The user equipment uses a home address assigned to the user equipment as a source IP address of the first binding update message. The method further includes sending a second binding update message from the user equipment over the second access network to create a second binding cache entry at the home agent. The user equipment receives packets from the home agent through the first access network and the second access network based on the first binding cache entry and the second binding cache entry.

CROSS-REFERENCE TO RELATED APPLICATIONS

This disclosure claims the benefit of U.S. Provisional Application No.61/086,632, filed Aug. 6, 2008, which is incorporated herein byreference.

FIELD

The present disclosure generally relates to wireless networks.

BACKGROUND

The 3rd Generation Partnership Project (3GPP) is a collaboration betweengroups of telecommunications associations, to make a globally applicablethird generation (3G) mobile phone system specification within the scopeof the International Mobile Telecommunications-2000 project of theInternational Telecommunication Union (ITU). FIG. 1 illustrates a 3GPParchitecture for multiple access in a non-roaming scenario, and FIG. 2illustrates a 3GPP architecture for multiple access in a roamingscenario. The architectures depicted in FIGS. 1 and 2 show the scenariosin whichs a client-based mobility protocol S2c—i.e., DSMIPv6 (Dual stackMobile IPv6)—is used for connectivity and mobility between 3GPP accessesand non-3GPP accesses. S2c is described in more detail in 3GPP TS23.402, which is incorporated herein by reference. The mechanismsspecified in 3GPP TS 23.402 can be used to connect a user equipment (UE)(or mobile terminal) in parallel to an evolved packet core (EPC) via a3GPP access network and a non-3GPP access network towards differentpacket data networks (PDNs).

Two Internet Engineering Task Force (IETF) specifications—IETFdraft-ietf-monami6-multiplecoa-08, and IETFdraft-ietf-mext-flow-binding-00a describe techniques for supportingmultiple IP flows over different accesses. The techniques are based onExtensions to DSMIPv6 where a UE can perform multiple CoA (Care-ofAddress) registrations for the same HoA (Home Address) with the HA (HomeAgent), and traffic is routed to the different CoAs based on flowbinding (i.e., traffic descriptors that filter the traffic and route thetraffic to the correct CoAs—downlink packets addresses to the UE arereceived by the HA, the filters are applied, and packets are routedtowards the CoA corresponding to the matching filter). It is thereforepossible to extend S2c in 3GPP (i.e., the interface based on DSMIPv6) inorder to allow a UE to be connected simultaneously to the same PDN viadifferent accesses and to move IP flows between the different accesses.

Specifically, the techniques include the following features. MultipleDSMIPv6 CoAs registrations occur at the DSMIPv6 level with the HA (HomeAgent)/PGW (PDN Gateway). The different CoAs are obtained over differentaccess networks. The different CoAs are then used simultaneously by theUE. One Binding Cache Entry (BCE) is created for each CoA. The mappingbetween HoA and CoA is no more a one-to-one but one to many. DSMIPv6 BUs(Binding Update messages) can contain more than one CoAs. A BID (BindingIdentifier) is used to univocally identify the HoA-CoA mapping. A BU(Binding Update) contains as many BID options as the number of CoAs inthe BU. DSMIPv6 BUs can contain description of flows associated witheach CoA. Each BU can contain a FID (Flow ID) option. The FID optionincludes a flow identifier and a flow description and a pointer to therespective BID. The routing of UL (uplink) and DL (downlink) packets isperformed based on these associations. For example, FIG. 3 illustratesan example binding cache in a home agent (HA)/packet data networkgateway (PGW) when multiple CoAs are registered for the same HoA withdifferent binding descriptors.

The techniques described in the IETF specifications mentioned above,however, do not apply completely to 3GPP networks. In fact, in 3GPP someaccesses (typically the 3GPP specific access technologies, e.g., WCDMAor LTE) are considered “home link” from a DSMIPv6 point of view. Whatthat means is that the UE, when connected over such access technologies,shall not use a DSMIPv6 tunnel to obtain connectivity. This isrepresented in FIGS. 1 and 2 by the presence of a dotted line S2cinterface (e.g., DSMIPv6) that indicates that only DSMIPv6 signaling canbe exchanged over 3GPP accesses, but no DSMIPv6 tunneling is used. FIGS.4 and 5 respectively illustrate this scenario.

In FIG. 4, Access #1 corresponds to the home link for the UE from aDSMIPv6 perspective (e.g., Access #1 is the serving gateway in a 3GPParchitecture), and Access #2 is not the home link. Because the UE is onthe home link, no CoA is assigned to the UE and, therefore, there are nomappings between an HoA and CoAs. Accordingly, both IP flows A and B arerouted through Access #1. In FIG. 5, Access #1 corresponds to the homelink for the UE from a DSMIPv6 perspective (e.g., Access #1 is theserving gateway in a 3GPP architecture), and Access #2 is not the homelink. For IP flow B, the UE is on the home link for DSMIPv6, therefore,no CoA is assigned. For IP flow A, the UE is not on the home link forDSMIPv6, therefore, a CoA1 is assigned. A mapping between the HoA andCoA1 must be created (including traffic filters/descriptors) at theHA/PGW.

Current techniques for providing multiple accesses to a UE are based onthe idea that when a UE is connected to a PDN over two accesses, the UEis assigned one CoA over each access. In practice, there is presently noway to allow a BCE (binding cache entry) that would have flowdescriptors for directing traffic either to the CoA or to the HoA, sinceno BCE is created unless there is a CoA, and therefore an entry for theHoA cannot be created. In FIGS. 1 and 2 the UE is connected on the homelink when the UE is using a 3GPP access, and is not on the home linkwhen using a non-3GPP access. In such scenario the UE is providedconnectivity either using PMIPv6 (Proxy Mobile IPv6) over an S5interface, or the GTP (GPRS Transport Protocol) protocol.

An additional scenario is when a UE can also be connected via two-homelinks is shown in FIG. 6. As shown in FIG. 6, IP flow A is routedthrough a first home link on Access #1, IP flow B is routed through asecond home link on Access #2, and IP flow C is routed through anon-home link on Access #3. Regarding IP flow C, the UE is not on thehome link, therefore, a CoA1 is assigned to the UE.

In such case, in fact, the UE using simultaneously a 3GPP access (wherethe connectivity is provided either with PMIPv6 or GTP) and a non 3GPPaccess and being connected over the non-3GPP access using PMIPv6 (i.e.,S2a or S2b are used and they use PMIPv6) as described in FIGS. 8 and 9.In such case, the UE is on two home links from a point of view ofDSMIPv6, and no DSMIPv6 tunneling shall be used. This specific scenariois not described in this invention. However an extended scenario wherethe UE is connected on two access that are home link for the UE and athird access that is not home link for the UE is described.

A final component of the problem is related to the scenario where the UEconnects first on a link that is not home link (i.e. a non-3GPP accessusing DSMIPv6) and subsequently to a 3GPP access. In currentspecifications, when the UE connects to a 3GPP access, the UE performsan attach procedure. Two types of attach procedures are defined—an“initial attach” and a “handover”. “Initial attach”: during the attachprocedure, the UE provides an indication of Attach Type as “initialattach”. This is used when the UE is actually connecting to the networkfor the first time and therefore it has no IP address allocated (i.e.,no HoA) nor a PDN GW/HA is allocated to serve the UE. In such case, thenetwork selects a new PDN GW and assigns a new HoA to the UE.“Handover”: during the attach procedure, the UE provides an indicationof Attach Type as “handover”. This is used when the UE is actuallyalready connected over another access and it is handing over theconnection to the 3GPP access. In such case the UE has an IP addressallocated (i.e., HoA) over the previous access and a PDN GW/HA isallocated to serve the UE. In such case, the network does not select anew PDN GW and does not assign a new HoA to the UE, but simply switchthe connectivity from the old access to the new access.

FIG. 8 illustrates a procedure 800 including steps involved in aninitial attach, which steps are further described in 3GPP TS 23.401(which is incorporated herein by reference). Note that the procedure forinitial attach over 3GPP is repeated also during handover from non-3GPP,as described in the steps, and shown in FIGS. 9 and 10.

Referring first to FIG. 8, note that for a PMIP-based S5/S8, proceduresteps (A), (B), and (C) are defined in TS 23.402. Steps 7, 10, 14, 15and 16 concern GTP based S5/S8. Also note that the steps in (D) areexecuted only upon handover from non-3GPP access. Additionally, only thekey steps of FIG. 8 are described below. At step 1, the UE initiates theAttach procedure by the transmission, to the eNodeB, of an AttachRequest (IMSI or old GUTI, Attach Type, . . . ) message. Attach Typeindicates “Handover” when the UE has already an activated PDN GW/HA dueto mobility with non-3GPP accesses. The eNodeB . . . forwards the AttachRequest message to the new MME (step 2).

At step 13, if the PDN subscription context contains a dynamicallyallocated PDN GW identity and the Attach Type does not indicate“Handover”, the MME may select a new PDN GW as described in clause PDNGW selection function, e.g., to allocate a PDN GW that allows for moreefficient routing. If the PDN subscription profile contains no PDN GWaddress for the default PDN and the Attach Type indicates “Handover”,the MME select a new PDN GW as described in clause PDN GW selectionfunction. The new MME selects a Serving GW, then the new MME sends aCreate Default Bearer Request ( . . . , PDN GW address, PDN Address, . .. , Handover Indication, . . . ) message to the selected Serving GW.Handover Indication is included if the Attach type indicates handover.

At step 14, the Serving GW sends a Create Default Bearer Request ( . . ., PDN Address, . . . , Handover Indication, . . . ) message to the PDNGW indicated by the PDN GW address received in the previous step. Atstep 15, if dynamic PCC is deployed, and the Handover Indication is notpresent, the PDN GW performs an IP-CAN Session Establishment procedureas defined in TS 23.203, and thereby obtains the default PCC rules forthe UE. If dynamic PCC is deployed and the Handover Indication ispresent, the PDN GW executes a PCEF-Initiated IP-CAN SessionModification procedure with the PCRF as specified in TS 23.203 to obtainthe rules required for the PDN GW in the VPLMN or HPLMN to function asthe PCEF for all the active sessions the UE has established with the newIP-CAN type as a result of the handover procedure. If, however, dynamicPCC is not deployed, the PDN GW may apply local QoS policy.

At step 16, the PDN GW returns a Create Default Bearer Response ( . . .) message to the Serving GW when the Handover Indication is present, thePDN GW does not yet send downlink packets to the SGW; the downlink pathis to be switched at step 22 a. At step 22, the new MME sends an UpdateBearer Request ( . . . , Handover Indication) message to the Serving GW.At step 22 a, if the Handover Indication is included in step 22, theServing GW sends an Update Bearer Request (Handover Indication) messageto the PDN GW to prompt the PDN GW to tunnel packets from non 3GPP IPaccess to 3GPP access system and immediately start routing packets tothe Serving GW for the default and any dedicated EPS bearersestablished. At step 22 b, the PDN GW acknowledges by sending UpdateBearer Response to the Serving GW.

At step 23, the Serving GW acknowledges by sending Update BearerResponse (EPS Bearer Identity) message to the new MME. The Serving GWcan then send its buffered downlink packets. At step 24, after the MMEreceives Update Bearer Response (EPS Bearer Identity) message, if Attachtype does not indicate handover, and an EPS bearer was established andthe subscription data indicates that the user is allowed to performhandover to non-3GPP accesses, and if the MME selected a PDN GW that isdifferent from the PDN GW identity which was indicated by the HSS in thePDN subscription context, the MME shall send an Update Location Requestincluding the APN and PDN GW identity to the HSS for mobility withnon-3GPP accesses. Note that in the case of a handover from a non-3GPPaccess, the PDN GW initiates resource allocation deactivation procedurein the trusted/untrusted non-3GPP IP access.

Step 8 of FIG. 8 results also in storing in PCC the IP-CAN indicationfor the connection (i.e. 3GPP access). In case of UE connected first toan access that is not home link and then connecting to an access that ishome link (i.e. a 3GPP access) and moving some flows from the non-3GPPaccess to the 3GPP access, neither indication works.

In fact: “Initial attach”: since in such case the network selects a newPDN GW and assign a new HoA to the UE, the UE ends up with a differentHoA and cannot moves the flows over from the non-3GPP access.“Handover”: in this case the network would typically switch theconnectivity from the old access to the new access if the old access isconnected using PMIP, since “Handover” is used to provide IP addresspreservation, and the UE would then delete the S2c BCE at the end of thehandover. FIGS. 9 and 10 describe this type of handover as currentlydefined where all the flows are being moved to the new access.

Regarding the steps shown in FIG. 9, the UE uses a trusted or untrustednon-3GPP access system (step 1). For example, the UE can have a DSMIPv6session with the PDN GW. In step 2, the UE discovers and attaches to the3GPP access. In step 3, the UE sends a BU (lifetime) to the PDN GW tode-register its DSMIPv6 binding, as defined indraft-ietf-mip6-nemo-v4traversal (which is incorporated herein byreference) that was created while the UE was in non-3GPP access system.The PDN GW responds with a BA message as defined indraft-ietf-mip6-nemo-v4traversal. Step 3 corresponds to deleting the BCEfor the connection with S2c over the old link.

Referring to FIG. 10, in step 1, the UE uses a trusted or untrustednon-3GPP access system and is served by a PDN GW (as PMIPv6 LMA or MIPv4HA). In step 2, the UE discovers the E-UTRAN access and determines totransfer its current sessions (i.e., handover) from the currently usednon-3GPP access system to E-UTRAN. In step 3, the UE sends an AttachRequest to the MME with Attach Type indicating “Handover” Attach. Instep 4, the MME contacts the HSS and authenticates the UE. The MMEreceives information on the PDNs the UE is connected to over thenon-3GPP access in the Subscriber Data obtained from the HSS.

In step 5, after successful authentication, the MME performs locationupdate procedure and subscriber data retrieval from the HSS. Since theAttach Type is “Handover” Attach, the PDN GW address conveyed to the MMEwill be stored in PDN subscription context. In step 6, for connectivityto multiple PDNs, even if the UE had disconnected from the Default PDNbefore the handover, the MME selects a serving GW as described in TS23.401 and sends a Create Default Bearer Request ( . . . , PDN-GWaddress, Handover Indication) message to the selected Serving GW. Sincethe Attach Type is “Handover” Attach, a Handover Indication informationis included. In step 7, the Serving GW sends a Create Default BearerRequest (Handover Indication) message to the PDN-GW in the VPLMN orHPLMN. Since the MME includes Handover Indication information in CreateDefault Bearer Request message, the Serving GW includes this informationin Create Default Bearer Request message. Since Handover Indication isincluded, the PDN GW should not switch the tunnel from non-3GPP IPaccess to 3GPP access system at this point.

In step 8, since Handover Indication is included, the PDN GW executes aPCEF-Initiated IP CAN Session Modification Procedure with the PCRF asspecified in TS 23.203 to obtain the rules required for the PDN GW inthe VPLMN or HPLMN to function as the PCEF for all the active sessionsthe UE has established with the new IP-CAN type as a result of thehandover procedure. In step 9, the PDN GW responds with a Create DefaultBearer Response message to the Serving GW. In step 10, the Serving GWreturns a Create Default Bearer Response message to the MME. In step 11,Radio and Access bearers are established at this step in the 3GPPaccess. In step 12, the MME sends an Update Bearer Request ( . . . ,Handover Indication) message to the Serving GW.

In step 13, since the Handover Indication is included in step 12), theServing GW sends an Update Bearer Request message to the PDN GW toprompt the PDN GW to tunnel packets from non 3GPP IP access to 3GPPaccess system and immediately start routing packets to the Serving GWfor the default and any dedicated EPS bearers established. In step 14,the PDN GW acknowledges by sending Update Bearer Response to the ServingGW. In step 15, the Serving GW acknowledges by sending Update BearerResponse message to the MME. In step 16, the UE sends and receives dataat this point via the E-UTRAN system. In step 18, the PDN GW shallinitiate resource allocation deactivation procedure in thetrusted/untrusted non-3GPP IP access.

Step 3 of FIG. 9 implies that the BCE corresponding to all the flows isdeleted, and step 18 of FIG. 10 implies that all resources on non-3GPPare released. However, in theory one could think of using the “handover”indication for the specific case where the “handover” indication isprovided. In fact the UE may not delete the BCE and instead modify theBCE to setup some filters to forward some flows on the 3GPP access andsome on the non-3GPP access. However, step 8 of FIG. 10 results also inupdating PCC with the IP-CAN indication for the connection (before thehandover it identifies the non-3GPP access and is now modified to 3GPPaccess), even if some flows are maintained over the non-3GPP access.This may result in incorrect charging, deletion of flows based onpolicies, and other unwanted behaviors.

SUMMARY

In general, in one aspect, this specification describes a mechanism fora mobile node (connected to a packet data network over a first accessnetwork and a second access network) to enable the network to routepackets to the UE over the correct access network and to enable the UEto perform handoff of IP flows from one access network to the other. Thefirst access network can be a home link for the mobile node and thesecond access network can be a foreign link.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a 3GPP architecture for multiple access in anon-roaming scenario.

FIG. 2 illustrates a 3GPP architecture for multiple access in a roamingscenario.

FIG. 3 illustrates an example binding cache in a home agent (HA)/packetdata network gateway (PGW) when multiple CoAs are registered for thesame HoA with different binding descriptors.

FIG. 4 illustrates a scenario of simultaneous connectivity throughmultiple heterogeneous accesses.

FIG. 5 illustrates a scenario of simultaneous connectivity throughmultiple heterogeneous accesses.

FIG. 6 illustrates a scenario in which a UE is connected via two-homelinks.

FIGS. 7A-7E illustrate various scenarios of simultaneous connectivitythrough multiple heterogeneous accesses.

FIG. 8 illustrates a handover procedure in accordance with oneimplementation.

FIG. 9 illustrates a handover procedure in accordance with oneimplementation.

FIG. 10 illustrates a handover procedure in accordance with oneimplementation.

FIG. 11 illustrates a new flag in a reserved field of a Binding Updatemessage.

FIG. 12 illustrates a scenario in which the UE connects to a foreignlink first, and then connects to a home link.

FIG. 13 illustrates a scenario in which the UE first connects to a homelink, and then connects to a foreign link.

FIG. 14 illustrates a handover procedure in accordance with oneimplementation.

FIG. 15 illustrates a scenario in which a UE first connects to a foreignlink, and then connects to a home link.

FIG. 16 illustrates a scenario in which a UE first connects to a homelink, and then connects to a foreign link.

FIG. 17 illustrates a scenario in which a UE connects to both home linkand foreign link, and then the UE drops the connection over the foreignlink.

FIG. 18 illustrates a scenario in which a UE first connects to a foreignlink, and then connects to a home link.

FIG. 19 illustrates a scenario in which a UE first connects to a homelink, and then connects to a foreign link.

FIG. 20 illustrates a handover procedure in accordance with oneimplementation.

FIG. 21 illustrates a procedure when a UE connects first to a foreignlink and then connects to a plurality of home links.

FIG. 22 illustrates a handover procedure in accordance with oneimplementation.

FIG. 23 illustrates a procedure for using DHCP or Routersolicitation/Advertisement messages to convey flow information when GTPis used.

FIG. 24 illustrates a procedure in which DHCP messages are used toconvey the flow information when PMIP is used.

FIG. 25 illustrates a procedure when Route Solicitation/RouterAdvertisement messages are used to convey the flow information when PMIPis used.

FIG. 26 is a block diagram of a data processing system suitable forstoring and/or executing program code.

DETAILED DESCRIPTION

As discussed above, Current 3GPP specifications do not specify how a UEcan simultaneously access a network through multiple heterogeneousaccesses. For example, FIGS. 7A-7E illustrate various scenarios ofsimultaneous connectivity through multiple heterogeneous accesses.Simultaneous connectivity through multiple heterogeneous accesses isuseful since multi-radio UEs start to become more common (e.g.,3GPP+WLAN in the home environment) and the UEs may have a form factorsdifferent than “phone”. As a result, a UE may be anyway connectedthrough different accesses to the same PDN. In such scenarios it ispossible to use the UE's ability to connect via multiple accesses inparallel in order, e.g., to increase the overall bandwidth experiencedby the UE to a given PDN. In such scenarios IP flows could bedynamically switched between cellular and other accesses where, e.g.“less valuable” high volume traffic could be dynamically “offloaded” tounlicensed accesses. IP flows would still switched between differentaccesses due to an actual handover, e.g., when one access is no longeravailable. In FIG. 7A, the UE initially has connectivity through Access#1, and both IP flows A and B are routed through Access #1. In FIG. 7B,the UE detects another access (Access #2), and IP flow A is routedthrough Access #2. In FIG. 7C, the UE adds an additional IP flow (IPflow C) over Access #2. In FIG. 7D, the UE moves towards an area ofcoverage in which only Access #1 is available. As shown in FIG. 7E, allthe IP flows A, B, C are moved to Access #1. Various scenarios aredescribed in detail below.

Scenario 1: UE Connected to One Home Link and One Foreign Link

The following three embodiments are defined in this invention for thescenario in which the UE connects to one home link and one foreign linksimultaneously:

HA/PGW Binding Cache Establishment Through Home Link

In one embodiment, the UE sends mobility signaling messages over thehome link in order to create a Binding Cache entry containing flowfilters for the home link in the Home Agent. Such mobility signallingmessages sent over the home link could be either a Binding Updatemessage with an indication, e.g., a new flag or a new option or aspecial value in an existing field, or a Generic Notification message ora new type of mobility header message. In this embodiment, we focus theuse of the Binding Update message for this purpose.

As specified in the Mobile IP specification, such as RFC 3775 (which inincorporated herein by reference), the Binding Update message can besent over the home link only to remove the Binding Cache entry;otherwise, the Binding Update message may result in conflicts, forexample both the Home Agent and the mobile node need to defend the samehome address. Therefore, to enable simultaneous connectivity overmultiple access networks, the Home Agent needs to behave differentlyfrom specified in RFC 3775 when receiving a Binding Update message overthe home link. The Home Agent reacts based on the indication carried inthe Binding Update message and its policy and configuration.

When sending the Binding Update message over the home link to create aBinding Cache entry, the UE must use its home address as the source IPaddress of the Binding Update message. The indication to the Home Agentcan be the lifetime field set as a non-zero value and/or a new flag inthe reserved field of the Binding Update message as shown in FIG. 11and/or a BID mobility option (as described in IETF draftdraft-ietf-monami6-multiplecoa-08) and a Flow Identification option (asdescribed in IETF draft draft-ietf-mext-flow-binding-00). FIG. 11illustrates Flow Binding on the home link (F)—i.e., a new (F) flag inthe Binding Update message. The new flag (F) that indicates that theBinding Update is sent over the home link and is used for creating aBinding Cache entry for flow binding over the home link.

Once the Home Agent receives such Binding Update message from the UE,after verification, the Home Agent will create an additional BindingCache entry for the same home address with the requested flowinformation. In the following we describe the procedures in details intwo cases: 1) the UE connects to a foreign link first, and then connectsto a home link; 2) the UE connects to a home link first, and thenconnects to a foreign link.

FIG. 12 illustrates the first case in which the UE first connects to aforeign link, and then connects to a home link. As indicated by (1), theUE first configures an address from a local access network. The UEdetects the address and connects to a foreign link by running a homelink detection mechanism, for example, by running the IKEv2 with theHome Agent during bootstrapping. The UE sends a Binding Update messageover the foreign link to set up a Binding Cache entry in the Home Agent.The UE may specify the flow that the UE wants to direct to the foreignlink in the Binding Update message. The Home Agent replies to the UEwith a Binding Acknowledgement message to indicate the status of bindingregistration.

As indicated by (2), the UE then discovers and obtains an IP addressfrom another access network. By performing a home link detectionmechanism, the UE connects to the home link. In the example of FIG. 12,the UE plans to keep network connectivity over both the foreign link andthe home link, therefore, the UE sends a Binding Update message over thehome link with such indication to the Home Agent to request certain flowto be directed to the home link. After the Home Agent processes suchBinding Update message, the Home Agent creates another Binding Cacheentry for the UE. In such Binding Cache entry, the care-of address fieldmay be set as either the home address or a different special or dummyvalue to indicate that the flow associated with this entry is forwardedto the UE via a home link. The Home Agent replies to the UE with aBinding Acknowledgement message to indicate the status of bindingregistration. With this approach, the UE can modify the flows in theBinding Cache entry by sending a Binding Update message over any link.

FIG. 13 illustrates the second case in which the UE first connects to ahome link, and then connects to a foreign link. First, the UE configuresan address from a local access network. The UE detects the address andconnects to a home link by running a home link detection mechanism, forexample, by running the IKEv2 with the Home Agent during bootstrapping.The UE may or may not send a Binding Update message over the home linkto set up a Binding Cache entry in the Home Agent at this time. The UEthen discovers and obtains an IP address from another access network. Byperforming a home link detection mechanism, the UE connects to theforeign link. The UE may specify the flow that the UE wants to direct tothe foreign link in the Binding Update message. The Home Agent repliesto the UE with a Binding Acknowledgement message to indicate the statusof binding registration.

The UE wants to keep network connectivity over both the foreign link andthe home link. If the UE has not sent a Binding Update message over thehome link upon attachment, the UE then sends a Binding Update messageover the home link with such indication to the Home Agent to requestcertain flow to be directed to the home link. If the UE has already senta Binding Update message over the home link upon attachment, the UE maysend another Binding Update message over the home link to modify theBinding Cache entry for the home link.

After the Home Agent processes such Binding Update message, the HomeAgent creates or modifies the Binding Cache entry for the UE. In suchBinding Cache entry, the care-of address field may be set as either thehome address or a different special or dummy value to indicate that theflow associated with this entry is forwarded to the UE via a home link.The Home Agent replies to the UE with a Binding Acknowledgement messageto indicate the status of binding registration. With this approach, theUE can modify the flows in the Binding Cache entry by sending a BindingUpdate message over any link.

An example description of how the handover actually takes place and howPCC interaction takes will now be provided. UE has flows 1 and 2 onnon-3GPP with S2c. UE decides to move flow 1 to 3GPP. UE performs anhandover from non-3GPP to 3GPP using S2c (based on FIGS. 9 and 10, butwith the modifications described here and shown procedure 1400 of FIG.14) and the UE provides indication of Attach Type=“additional attach”(or a value with similar meaning). The original step 14 of FIG. 8 andstep of FIG. 10 now carries the Handover Indication=“additional attach”(or a value with similar meaning) to PDN GW and PDN GW does not performthe original step 15 of FIG. 8 and step 8 of FIG. 10 when HandoverIndication=“additional attach” (or a value with similar meaning). Nowthe UE is attached on 3GPP but the data is still flowing over non-3GPP.

The UE, once attach is done, sends BU (on either access) to modify theflow binding and create the BCE flow binding for the flows to be sentover the 3GPP access (i.e., directly routed to the HoA). In reaction,the PDN GW performs the original step 15 of FIG. 8 and step 8 of FIG. 10to modify the information in the PCC. The PDN GW may receiveconfirmation of the modification and that the flows moved to the 3GPPaccess are allowed, or may get an error message that indicates the UE isnot allowed to move the flows. The UE in such case: (1) needs to knowthat it has to disconnect from the 3GPP access: the UE does so whenreceiving a BA with a rejection code (e.g., the “128 Flow bindingrejected, reason unspecified” error code defined in the flow bindingsolution, or using a new “not allowed” rejection), and (2) alwaysrequests for a BA (Binding Update DSMIPv6 message). BA is sent only whenthe UE requests the BA, and the UE does not exchanged traffic over thelink until the BA is received. The UE is configured to request the BA.For UEs where the DSMIPv6 may reside in, e.g., a laptop and not the UEitself, there may be some unexpected behaviors since it is not possibleto force the UE to request a BA.

Alternatively, in 3GPP the PDN GW always sends a BA upon receiving a BUmodifying flow bindings, to ensure the UE receives the authorization forthe modifications. That would work both for pure 3GPP UEs and, e.g.,laptops connected to a 3GPP UE.

FIG. 14 illustrates a modified handover procedure with a modified attachindication and PCC interactions. In step 1, the UE uses a trusted oruntrusted non-3GPP access system. In one example, the UE has a DSMIPv6session with the PDN GW. In step 2, the UE discovers and attaches to the3GPP access. In step 3, the UE sends an Attach Request to the MME withAttach Type indicating “Additional Attach”. In step 4, the MME contactsthe HSS and authenticates the UE. The MME receives information on thePDNs the UE is connected to over the non-3GPP access in the SubscriberData obtained from the HSS. In step 5, after successful authentication,the MME performs location update procedure and subscriber data retrievalfrom the HSS. Since the Attach Type is “Additional Attach”, the PDN GWaddress conveyed to the MME will be stored in PDN subscription context.

In step 6, for connectivity to multiple PDNs, even if the UE haddisconnected from the Default PDN before the handover, the MME selects aserving GW as described in TS 23.401 and sends a Create Default BearerRequest ( . . . , PDN-GW address, Handover Indication) message to theselected Serving GW. Since the Attach Type is “Additional Attach”Attach, a Handover Indication=“Additional Attach” (or an AdditionalAttach Indication) information is included. In step 7, the Serving GWsends a Create Default Bearer Request (Handover Indication=“AdditionalAttach” or an Additional Attach Indication) message to the PDN-GW in theVPLMN or HPLMN. Since the MME includes Handover Indication informationin Create Default Bearer Request message, the Serving GW includes thisinformation in Create Default Bearer Request message. Since HandoverIndication=“Additional Attach” (or an Additional Attach Indication) isincluded, the PDN GW should not switch the tunnel from non-3GPP IPaccess to 3GPP access system at this point.

In step 8, the PDN GW responds with a Create Default Bearer Responsemessage to the Serving GW. In step 9, the Serving GW returns a CreateDefault Bearer Response message to the MME. In step 10, Radio and Accessbearers are established at this step in the 3GPP access. In step 11, theMME sends an Update Bearer Request ( . . . , HandoverIndication=“Additional Attach” or an Additional Attach Indication)message to the Serving GW. In step 12, since the Handover IndicationHandover Indication=“Additional Attach” (or an Additional AttachIndication) is included in step 12), the Serving GW sends an UpdateBearer Request message to the PDN GW to prompt the PDN GW to tunnelpackets from non 3GPP IP access to 3GPP access system and immediatelystart routing packets to the Serving GW for the default and anydedicated EPS bearers established.

In step 13, the PDN GW acknowledges by sending Update Bearer Response tothe Serving GW. In step 14, the Serving GW acknowledges by sendingUpdate Bearer Response message to the MME. In step 15, the UE isconnected over E-UTRAN but does not yet send and receive data at thispoint via the E-UTRAN system. In step 16, the UE sends a BU (on thenon-3GPP link in this scenario, and on the home link in the scenariodescribed later on in the document) to modify the flow binding andcreate the BCE flow binding for the flows to be sent over the 3GPPaccess (i.e., directly routed to the HoA). In one implementation, a 3GPPUE always requests for a BA (Binding Update DSMIPv6 message), and the UEdoes not exchanged traffic over the new link until the BA is received.The UE is configured to request the BA. For UEs where the DSMIPv6 mayreside in, e.g., a laptop and not the UE itself, there may be someunexpected behaviors since it is not possible to force the UE to requesta BA.

In step 17, the PDN GW executes a PCEF-Initiated IP CAN SessionModification Procedure with the PCRF to obtain the rules required forthe PDN GW in the VPLMN or HPLMN to function as the PCEF for all theactive sessions the UE has established with the new IP-CAN type as aresult of the handover procedure. The PDN GW also indicates which IPFlows are using IP-CAN=3GPP and which are using IP-CAN=non-3GPP. The PDNGW may receive confirmation of the modification and that the flows movedto the 3GPP access are allowed, or may get an error message thatindicates the UE is not allowed to move the flows.

In step 18, The PDN GW returns a BA message to the UE. The UE in suchcase needs to know that it has to disconnect from the 3GPP access. TheUE does so when receiving from the PDN GW a BA with a rejection code(e.g., the “128 Flow binding rejected, reason unspecified” error codedefined in the flow binding solution, or using a new “not allowed”rejection). If instead the UE is allowed to route the flows over the newaccess, the BA does not contain an error code. The PDN GW may return theBA only when the UE requests it in the BU, or alternatively the PDN GWalways sends a BA upon receiving a BU modifying flow bindings, to ensurethe UE receives the authorization for the modifications. That would workboth for pure 3GPP UEs and, e.g., laptops connected to a 3GPP UE.

HA/PGW Binding Cache Establishment Through Non-Home Link

In one embodiment, information of flows directed to the home link iscarried either in the Binding Update message sent over the foreign linkor in the Binding Update message for de-registration sent over the homelink. In such Binding Update messages, the UE includes the FlowIdentification option and the Binding Identifier Mobility Option for thehome link, and optionally together with those options for the foreignlink. Described below are procedures for the following three cases: 1)the UE first connects to a foreign link, and then connects to a homelink (FIG. 15); 2) the UE first connects to a home link, and thenconnects to a foreign link (FIG. 16); 3) the UE connects to both homelink and foreign link, and then the UE drops the connection over theforeign link (FIG. 17).

Referring first to the case illustrated in FIG. 15, The UE configures anaddress from a local access network. the UE detects that the UE isconnected to a foreign link by running a home link detection mechanism,for example, by running the IKEv2 with the Home Agent duringbootstrapping. The UE sends a Binding Update message over the foreignlink to set up a Binding Cache entry in the Home Agent. The UE mayspecify the flow that the UE wants to direct to the foreign link in theBinding Update message. The Home Agent replies to the UE with a BindingAcknowledgement message to indicate the status of binding registration.

The UE then discovers and obtains an IP address from another accessnetwork. By performing a home link detection mechanism, the UE realizesthat the UE is connected to the home link. The UE wants to keep networkconnectivity over both the foreign link and the home link, and the UEsends a Binding Update message over the foreign link with someindication to the Home Agent to request certain flow to be directed tothe home link. Optionally, the UE can modify the flows to be directed tothe foreign link in the same Binding Update message by including theBinding Identifier Mobility Option and Flow Identification MobilityOption for the foreign link. After the Home Agent processes such BindingUpdate message, the Home Agent creates another Binding Cache entry forthe UE. In such Binding Cache entry, the care-of address field may beset as either the home address or a different special or dummy value toindicate that the flow associated with this entry is forwarded to the UEvia a home link. The Home Agent replies to the UE with a BindingAcknowledgement message to indicate the status of binding registration.

Referring to the case illustrated in FIG. 16, the UE first configures anaddress from a local access network. The UE detects that the UE isconnected to a home link by running a home link detection mechanism, forexample, by running the IKEv2 with the Home Agent during bootstrapping.The UE does not send a Binding Update message over the home link to setup a Binding Cache entry in the Home Agent at this time.

The UE then discovers and obtains an IP address from another accessnetwork. By performing a home link detection mechanism, the UE realizesthat the UE is connected to the foreign link. If the UE wants to keepnetwork connectivity over both the foreign link and the home link, theUE specifies the flows that the UE wants to direct to the foreign linkand the home link in the Binding Update message by using multiple FlowIdentification options and Binding Identifier options for the home linkand the foreign link. After the Home Agent processes such Binding Updatemessage, the Home Agent creates the Binding Cache entries for the UE. Insuch Binding Cache entry for the home link, the care-of address fieldmay be set as either the home address or a different special or dummyvalue to indicate that the flow associated with this entry is forwardedto the UE via a home link. The Home Agent replies to the UE with aBinding Acknowledgement message to indicate the status of bindingregistration.

Referring to the case illustrated in FIG. 17, the UE already sets upflow binding for both the home link and the foreign link. When the UEwants to disconnect the connection over the foreign link, the UE sends aBinding Update message over the home link with the lifetime as zero forthe Binding Cache entry created for the foreign link. Such BindingUpdate message includes the Flow Identification option and BindingIdentifier option to modify the Binding Cache entry for the home link,for example, to direct the traffic forwarded over the foreign linkbefore to the home link instead. The description of how the handoveractually takes place and how PCC interaction takes place can be the sameas in conventional techniques, however, with the BU being sent over adifferent link.

Routing Configuration Based on Security Establishment

A third approach is to use the IKE informational exchange over the homelink to provide flow binding information for the home link. To do this,the IKE needs to be extended to carry flow information, for example bydefining a new type of Configuration Attributes, or a new type of Notifypayload, or a different type of payload. Note that such IKEinformational exchange is independent from the BU/BA message exchangeover the foreign link. The UE can start the IKEv2 Informational exchangeany time when there is an IKEv2 SA available between the UE and the HA.When the Home Agent receives such IKE information exchange messages, theHome Agent stores such information and uses such information for trafficforwarding. For example, when the Home Agent receives a packet destinedat the home address of the UE, the Home Agent may look up the BindingCache entry first, if no entry matches, the Home Agent turns to thestored information to decide how to forward the packet.

There are two cases: 1) the UE first connects to a foreign link, andthen connects to a home link (FIG. 18); and 2) the UE first connects toa home link, and then connects to a foreign link (FIG. 19).

Referring to the case illustrated in FIG. 18, the UE first configures anaddress from a local access network. The UE detects the UE connects to aforeign link by running a home link detection mechanism, for example, byrunning the IKEv2 with the Home Agent during bootstrapping. The UE sendsa Binding Update message over the foreign link to set up a Binding Cacheentry in the Home Agent. The UE may specify the flow that the UE wantsto direct to the foreign link in the Binding Update message. The HomeAgent replies to the UE with a Binding Acknowledgement message toindicate the status of binding registration.

The UE then discovers and obtains an IP address from another accessnetwork. By performing a home link detection mechanism, the UE realizesthe UE is connected to the home link. The UE wants to keep networkconnectivity over both the foreign link and the home link, the UE thenstarts an IKEv2 informational exchange with the Home Agent over eitherthe home link or the foreign link carrying the indication to requestcertain flow to be directed to the home link. In addition, the UE maysend the Binding Update message over the foreign link to update the flowbinding for the foreign link.

Referring to the case illustrated in FIG. 19, the UE first configures anaddress from a local access network. The UE detects that the UE isconnected to a home link by running a home link detection mechanism, forexample, by running the IKEv2 with the Home Agent during bootstrapping.The UE may or may not perform the IKEv2 informational exchange over thehome link with the Home Agent at this time. The UE then discovers andobtains an IP address from another access network. By performing a homelink detection mechanism, the UE realizes that the UE is connected tothe foreign link. The UE may specify the flow that the UE wants todirect to the foreign link in the Binding Update message. The Home Agentreplies to the UE with a Binding Acknowledgement message to indicate thestatus of binding registration. The UE wants to keep networkconnectivity over both the foreign link and the home link. The UE thenstarts the IKEv2 informational exchange with the Home Agent over eitherthe home link or the foreign link carrying the indication to requestcertain flow to be directed to the home link.

FIG. 20 illustrates a modified handover procedure 2000 in accordancewith one implementation. The handover procedure 2000 includes a modifiedattach indication and PCC interactions when the IKEv2 informationalexchange is used to update flow binding information. The steps involvedin FIG. 20 are discussed below.

Steps 1 to 15 are the same as described with respect to FIG. 14. In step16, the UE starts the IKEv2 informational exchange with the PDN GW bysending an IKEv2 informational request message (on the non-3GPP link oron the home link) to modify the flow binding and create the BCE flowbinding for the flows to be sent over the 3GPP access (i.e., directlyrouted to the HoA). In one implementation, the UE does not exchangetraffic over the new link until the IKEv2 information reply message isreceived. In step 17, the PDN GW executes a PCEF-Initiated IP CANSession Modification Procedure with the PCRF to obtain the rulesrequired for the PDN GW in the VPLMN or HPLMN to function as the PCEFfor all the active sessions the UE has established with the new IP-CANtype as a result of the handover procedure. The PDN GW also indicateswhich IP Flows are using IP-CAN=3GPP and which are usingIP-CAN=non-3GPP. The PDN GW may receive confirmation of the modificationand that the flows moved to the 3GPP access are allowed, or may get anerror message that indicates the UE is not allowed to move the flows.

In step 18, the PDN GW returns an IKEv2 informational reply message tothe UE. The UE in such case needs to know that the UE has to disconnectfrom the 3GPP access. The UE does so when receiving from the PDN GW areply message with a rejection code (e.g., a new “not allowed or failed”rejection code). Otherwise, the UE is allowed to route the flows overthe new access, and the IKEv2 reply message does not contain an errorcode.

Scenario 2: UE Connected to Two Home Links and a Third Non-Home Link

The UE may obtain network connectivity to the same Home Agent via threedifferent access networks, where two access networks are home links andone access network is the foreign link. For example the UE connects totwo links using PMIP or using PMIP on one link and using GTP on theother link. When PMIP is used, the Home Agent that performs the functionof the Local Mobility Anchor (LMA) maintains a Binding Cache entry wherethe IP address of the Mobile Access Gateway (MAG) is in the care-ofaddress field. In addition, the Home Agent can distinguish the BindingCache entry for PMIP from that for DSMIPv6 by associating a flag withthe Binding Cache entry as defined in IETFdraft-ietf-netlmm-proxymip6-18 (which is incorporated herein byreference).

HA/PGW Binding Cache Establishment Through Home Link

In one implementation, for scenario 2, the UE sends mobility signallingmessages over the home link in order to create a Binding Cache entrycontaining flow filters for the home link in the Home Agent. Suchmobility signalling messages could be either a Binding Update messagewith an indication, e.g., a new flag or a new option or a special valuein an existing field, or a Generic Notification message or a new type ofmobility header message. In one implementation, the Binding Updatemessage is used for this purpose. However, in this case, there are twohome links, and the Home Agent needs to determine the intended home linkfor the received mobility signalling message. To identify the home linkin the Binding Update messages sent by the UE to the HA, some indicationin addition to what is described in 3GPP TS 23.402 is needed. Suchindication can be access technology type, the link-layer identifier ofthe UE's connected interface on the access link or other information.

Furthermore, to enable simultaneous connectivity over multiple accessnetworks, the Home Agent needs to behave differently from specified inRFC 3775 when receiving a Binding Update message over the home link. TheHome Agent reacts based on the indication carried in the Binding Updatemessage and its policy and configuration. When sending the BindingUpdate message over the home link to create a Binding Cache entry, (inone implementation) the UE uses an assigned home address as the sourceIP address of the Binding Update message. The indication to the HomeAgent includes the lifetime field set as a non-zero value and/or a newflag in the reserved field of the Binding Update message as shown inFIG. 10 and/or a BID mobility option and a Flow Identification optionand the Mobile Node Link-layer Identifier Option as defined in IETFdraft-ietf-netlmm-proxymip6-18 (or IETF draftdraft-haley-mext-generic-notification-message-00 which is incorporatedherein by reference) and/or the Access Technology Type Option as definedin IETF draft-ietf-netlmm-proxymip6-18 (or IETF draftdraft-haley-mext-generic-notification-message-00) to distinguishdifferent home links.

Once the Home Agent receives such Binding Update message from the UE,after verification, the Home Agent creates an additional Binding Cacheentry for the same home address with the requested flow information.Such Binding Cache entry also contains the Access Technology Type optionand/or the Mobile Node Link-layer Identifier Option. The procedures forthe following two cases are described herein: 1) the UE connects to aforeign link first, and then connects to home links (FIG. 21); 2) the UEconnects to home links first, and then connects to a foreign link.

For the case illustrated in FIG. 21, the UE first configures an addressfrom a local access network. The UE detects that the UE is connected toa foreign link by running a home link detection mechanism, for example,the IKEv2 with the Home Agent during bootstrapping. The UE sends aBinding Update message over the foreign link to set up a Binding Cacheentry in the Home Agent. The UE may specify the flow that the UE wantsto direct to the foreign link in the Binding Update message. The HomeAgent replies to the UE with a Binding Acknowledgement message toindicate the status of binding registration.

The UE then discovers and obtains an IP address from the second accessnetwork. By performing some home link detection mechanisms, the UErealizes that the UE is connected to the home link. Assume that the PMIPis used for the UE to establish network connectivity to the HA on thisaccess network. The UE wants to keep network connectivity over both theforeign link and this home link, after finishing the PMIP based attachprocedure, the UE sends a Binding Update message over the home link withthe indication as described before to the Home Agent to request certainflow to be directed to the home link. The Home Agent uses the homeaddress/MN identifier and the access type and optionally the linkerlayer address to identify the PMIP Binding Cache entry. After the HomeAgent processes such Binding Update message, the Home Agent modifies thecorresponding PMIP Binding Cache entry for the UE. In such Binding Cacheentry, there is a flag indicating that this is a PMIP Binding Cacheentry, the care-of address field is set as the MAG's care-of address,the flow information, the access type and the link layer address for theinterface used on the access network. The Home Agent replies to the UEwith a Binding Acknowledgement message to indicate the status of bindingregistration.

The UE then discovers and obtains an IP address from the third accessnetwork. By performing a home link detection mechanism, the UE realizesthat the UE is connected to the home link. If the PMIP is used for theUE to establish network connectivity to the HA on this access network,the rest of the procedure is the same as discussed in the paragraphabove.

Otherwise, GTP can be used. The UE wants to keep network connectivityover both the foreign link and this home link, after finishing the GTPbased attach procedure, the UE sends a Binding Update message over theGTP based home link with the indication as described before to the HomeAgent to request certain flow to be directed to this home link. Bylooking up the Binding Cache by using the home address or the MNidentifier, and the access type and/or the layer 2 address, the HomeAgent cannot find a matching Binding Cache entry, because the GTPattachment does not create a Binding Cache entry. Therefore, after theHome Agent processes such Binding Update message, the Home Agent createsa Binding Cache entry for the UE. In such Binding Cache entry, there isa flag indicating that this cache entry is for the GTP based home link,the care-of address field contains the information of GTP user planetraffic forwarding or the pointer to such information, the associatedflow information, the access type and the link layer address for theinterface used on the access network. The Home Agent replies to the UEwith a Binding Acknowledgement message to indicate the status of bindingregistration.

With this approach, the UE can create and modify the flow informationover any link, even for the flow associated with a different link sincethe UE knows the flow identification associated with each link. The HomeAgent can use the combination of the home address/MN identifier, theFlow identification, the access type and the layer 2 address to locatethe Binding Cache entry. In case that the UE connects to either GTP orPMIP based home link first and then connects to a foreign link, theprocedure and the Binding Cache entries are similar with what isdescribed above. The solution described in the scenario 1 and FIG. 14applies to this scenario also.

HA/PGW Binding Cache Establishment Through Non-Home Link

In one implementation, for scenario 2, to create or modify the flowbinding for the home link and the foreign link, the UE sends the BindingUpdate message over the foreign link or over the home link whende-registering the Binding Cache entry for the foreign link. There areno differences from what is described before in the this implementationand that described in connection with scenario 1. In particular, thesolution described in the scenario 1 and FIG. 14 applies to thisscenario also.

Routing Configuration Based on Security Establishment

In one implementation, for scenario 2, the UE uses the IKEv2 informationexchange to set up flow binding for the home links. In oneimplementation, there is no difference from what is described before inIETF draft draft-ietf-mext-flow-binding-00.

FIG. 22 illustrates a modified handover procedure 2200 in accordancewith one implementation. The handover procedure 2200 includes a modifiedattach indication and PCC interactions when there are two home links andone foreign link. The steps involved in FIG. 22 are discussed below.

Steps 1 to 15 are the same as described in connection with FIG. 14. Instep 16, the steps in (A) are performed for the UE to set upconnectivity to the same PDN GW over another access network which is thehome link for the UE. The UE sends either a Binding Update message or anIKEv2 informational request message to the PDN GW (on the non-3GPP linkor on the home link) to modify the flow binding and create the BCE flowbinding for the flows to be sent over the home link accesses (i.e.,directly routed to the HoA). The UE does not exchange traffic over thenew home links until the Binding Acknowledgement message or the IKEv2information reply message are received.

In step 17, the PDN GW executes a PCEF-Initiated IP CAN SessionModification Procedure with the PCRF to obtain the rules required forthe PDN GW in the VPLMN or HPLMN to function as the PCEF for all theactive sessions the UE has established with the new IP-CAN type as aresult of the handover procedure. The PDN GW also indicates which IPFlows are using IP-CAN=3GPP and which are using IP-CAN=non-3GPP. The PDNGW may receive confirmation of the modification and that the flows movedto the 3GPP access are allowed, or may get an error message thatindicates the UE is not allowed to move the flows. In step 18, the PDNGW returns a Binding Ack message or an IKEv2 informational reply messageto the UE. The UE in such case needs to know that the UE has todisconnect from the 3GPP access. The UE does so when receiving from thePDN GW a reply with a rejection code (e.g., a new “not allowed orfailed” rejection code). Otherwise, the UE is allowed to route the flowsover the new access.

Scenario 3: UE Connected to Two Home Links

In this case, the UE simultaneously connects to two home links, eithertwo PMIP based home links or one GTP based and one PMIP based home link.If the UE is capable of DSMIPv6, the UE can modify the BCE entries andthe mapping of flows towards either the PMIP link or the GTP link (orone of the two PMIP links) by sending Binding Update messages over oneof the links.

This section focuses on the case where the UE does not support theDSMIPv6. Therefore, the UE needs to provide the flow information byextending the Router solicitation message or the DHCP request message(including DHCP information request message) or the GTP messageexchanged during attach procedure. Such extensions could be new payloadsor fields in the Router solicitation message or the DHCP message, or newPCOs (Protocol Configuration Options) in GTP messages containing theflow description and the flow identification. The Router Advertisementmessage and the DHCP reply message (including DHCP information replymessage) need to be extended to return the status of processing suchrequest to the UE.

In the GTP based 3GPP access network, the UE can communicate with thePDN GW (that performs the function of the LMA) directly by using theextended DHCP request message and the Router Solicitation message afterattach. Or the UE provides such information in the PCOs in the GTPmessage during attach. The PDN GW returns the extended RouterAdvertisement message and the DHCP reply message to the UE to indicatethe status.

In the PMIP based 3GPP access network, there are three methods. First,since the serving gateway is the DHCP relay and the PDN GW is the DHCPserver, after attach, the extended DHCP request message can be sent bythe UE to the serving gateway and then forwarded to the PDN GW. Thestatus will be returned to the UE in the extended DHCP reply message.Second, the serving gateway can also receive the Router solicitationmessage. Therefore, after attach, the UE can send the extended RouterSolicitation message to trigger the serving gateway to send a ProxyBinding Update message, which carries the flowing description and theflow identification information together with additional informationprovided by the UE, such as access network type and the link layeraddress, to the PDN GW. Third, the UE provides such information in thePCOs during attach which triggers the serving gateway to carry suchinformation in the Proxy Binding Update message to the PDN GW. In thelast two methods, after receiving and processing the PBU message, thePDN GW returns the status in a Proxy Binding Acknowledgement (PBA)message to the serving gateway and the serving gateway returns suchstatus in the extended Router Advertisement message (the second method)or in the PCOs (the third method) to the UE. In case that PCOs are usedto carry the flow information, the PCC interaction is performed at thesame steps shown in FIG. 8.

In the PMIP based non-3GPP access network, the UE can send the extendedRouter Solicitation message or the DHCP request message that carry theflowing description and the flow identification information togetherwith additional information provided by the UE, such as access networktype and the link layer address. Such messages will be received by theMobile Access Gateway (MAG) and the MAG forwards such information to thePDN GW (the Local Mobility Anchor, or LMA) in the Proxy Binding Update(PBU) message. After receiving the PBU message, the PDN GW creates orupdates the PMIP Binding Cache entry and sends back a Proxy BindingAcknowledgement (PBA) message to indicate the status to the MAG. MAGfinally forwards such status to the UE in the extended RouterAdvertisement message or DHCP reply message.

FIG. 23 illustrates a procedure 2300 for using DHCP or Routersolicitation/Advertisement messages to convey flow information when GTPis used. The steps involved procedure 2300 are discussed below.

In step 1, the attach procedure is performed as described in connectionwith FIG. 8. Then the UE sends the RS or DHCP request message with theflow information to the PDN GW. In step 2, the PDN GW executes aPCEF-Initiated IP CAN Session Modification Procedure with the PCRF toobtain the rules required for the PDN GW in the VPLMN or HPLMN tofunction as the PCEF for all the active sessions the UE has establishedwith the new IP-CAN type as a result of the handover procedure. The PDNGW also indicates which IP Flows are using IP-CAN=3GPP and which areusing IP-CAN=non-3GPP. The PDN GW may receive confirmation of themodification and that the flows moved to the 3GPP access are allowed, ormay get an error message that indicates the UE is not allowed to movethe flows.

In step 3, the PDN GW returns either a RA message or a DHCP replymessage to the UE. The UE in such case needs to know that it has todisconnect from the 3GPP access. The UE does so when receiving from thePDN GW a reply with a rejection code (e.g., a new “not allowed orfailed” rejection code). Otherwise, the UE is allowed to route the flowsover the new access.

FIG. 24 illustrates a procedure 2400 in which DHCP messages are used toconvey the flow information when PMIP is used. The steps involved inprocedure 2400 are discussed below.

In step 1, the attach procedure is performed as described in TS 23.402.Then the UE sends the DHCP request message with the flow information tothe serving GW. In step 2, the serving GW as a DHCP relay forwards suchDHCP request message to the PDN GW. In step 3, the PDN GW executes aPCEF-Initiated IP CAN Session Modification Procedure with the PCRF toobtain the rules required for the PDN GW in the VPLMN or HPLMN tofunction as the PCEF for all the active sessions the UE has establishedwith the new IP-CAN type as a result of the handover procedure. The PDNGW also indicates which IP Flows are using IP-CAN=3GPP and which areusing IP-CAN=non-3GPP. The PDN GW may receive confirmation of themodification and that the flows moved to the 3GPP access are allowed, ormay get an error message that indicates the UE is not allowed to movethe flows.

In step 4, the PDN GW as a DHCP server returns a DHCP reply message tothe Serving GW. In step 5, the Serving GW returns the DHCP reply to theUE. The UE in such case needs to know that it has to disconnect from the3GPP access. The UE does so when receiving from the PDN GW a reply witha rejection code (e.g., a new “not allowed or failed” rejection code).Otherwise, the UE is allowed to route the flows over the new access.

FIG. 25 illustrates a procedure 2500 when Route Solicitation/RouterAdvertisement messages are used to convey the flow information when PMIPis used. The steps shown in procedure 2500 are described below.

In step 1, the attach procedure is performed as described in TS 23.402.Then the UE sends the Route Solicitation request message with the flowinformation to the serving GW. In step 2, the serving GW sends a PBUmessage to the PDN GW to update the flow information. In step 3, the PDNGW executes a PCEF-Initiated IP CAN Session Modification Procedure withthe PCRF to obtain the rules required for the PDN GW in the VPLMN orHPLMN to function as the PCEF for all the active sessions the UE hasestablished with the new IP-CAN type as a result of the handoverprocedure. The PDN GW also indicates which IP Flows are usingIP-CAN=3GPP and which are using IP-CAN=non-3GPP. The PDN GW may receiveconfirmation of the modification and that the flows moved to the 3GPPaccess are allowed, or may get an error message that indicates the UE isnot allowed to move the flows.

In step 4, the PDN GW returns a PBA message to the Serving GW. In step5, based on the status code carried in the PBA message, the Serving GWreturns the Router Advertisement message to the UE (step 6). The UE insuch case needs to know that the UE has to disconnect from the 3GPPaccess. The UE does so when receiving a reply with a rejection code(e.g., a new “not allowed or failed” rejection code). Otherwise, the UEis allowed to route the flows over the new access.

One or more of the procedure steps described above can be performed byone or more programmable processors executing a computer program toperform functions by operating on input data and generating output.Generally, the invention can take the form of an entirely hardwareembodiment, an entirely software embodiment or an embodiment containingboth hardware and software elements. In one implementation, theinvention is implemented in software, which includes but is not limitedto firmware, resident software, microcode, etc. Furthermore, theinvention can take the form of a computer program product accessiblefrom a computer-usable or computer-readable medium providing programcode for use by or in connection with a computer or any instructionexecution system. For the purposes of this description, acomputer-usable or computer readable medium can be any apparatus thatcan contain, store, communicate, propagate, or transport the program foruse by or in connection with the instruction execution system,apparatus, or device. The medium can be an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system (orapparatus or device) or a propagation medium. Examples of acomputer-readable medium include a semiconductor or solid state memory,magnetic tape, a removable computer diskette, a random access memory(RAM), a read-only memory (ROM), a rigid magnetic disk and an opticaldisk. Current examples of optical disks include compact disk-read onlymemory (CD-ROM), compact disk-read/write (CD-R/W) and DVD.

FIG. 26 illustrates a data processing system 2600 (e.g., a UE) suitablefor storing and/or executing program code. Data processing system 2600includes a processor 2602 coupled to memory elements 2604A-B through asystem bus 2606. In other implementations, data processing system 2600includes more than one processor and each processor can be coupleddirectly or indirectly to one or more memory elements through a systembus. Memory elements 2604A-B can include local memory employed duringactual execution of the program code, bulk storage, and cache memoriesthat provide temporary storage of at least some program code in order toreduce the number of times the code must be retrieved from bulk storageduring execution. As shown, input/output or I/O devices 2608A-B(including, but not limited to, keyboards, displays, pointing devices,etc.) are coupled to data processing system 2600. I/O devices 2608A-Bmay be coupled to data processing system 2600 directly or indirectlythrough intervening I/O controllers (not shown).

In one implementation, a network adapter 2610 is coupled to dataprocessing system 2600 to enable data processing system 2600 to becomecoupled to other data processing systems or remote printers or storagedevices through communication link 2612. Communication link 2612 can bea private or public network. Modems, cable modems, and Ethernet cardsare just a few of the currently available types of network adapters.

Although the subject matter has been described in language specific tostructural features and/or methodological operations, the subject matterdefined in the appended claims is not necessarily limited to thespecific features or acts described above, including orders in which theacts are performed.

What is claimed is:
 1. A method for routing packets from a home agent toa user equipment through a first access network and a second accessnetwork, the method comprising: sending a first binding update messagefrom the user equipment over the first access network to create a firstbinding cache entry at the home agent, wherein an identification of afirst flow is included in (i) the first binding update message and (ii)the first binding cache entry, wherein the first access network is ahome link; subsequent to sending the first binding update message,sending a second binding update message from the user equipment over thesecond access network to create a second binding cache entry at the homeagent, wherein an identification of a second flow is included in (i) thesecond binding update message and (ii) the second binding cache entry,wherein the second access network is a foreign link; in response tosending the second binding update message, sending a third bindingupdate message from the user equipment over the first access network tomodify the first binding cache entry at the home agent, such that anidentification of a third flow is included in (i) the third bindingupdate message and (ii) the modified first binding cache entry, and suchthat a care-of address in the modified first binding cache entry is setto a dummy value to indicate that the third flow is to be forwarded tothe user equipment via the home link; and receiving, by the userequipment from the home agent, (i) a first plurality of packets throughthe first access network based on the identification of the third flowand (ii) a second plurality of packets through the second access networkbased on the identification of the second flow.
 2. The method of claim1, wherein the user equipment uses a home address assigned to the userequipment as a source IP address of the first binding update message. 3.The method of claim 1, wherein the first binding cache entry uses a homeaddress assigned to the user equipment as a care-of address of the userequipment.
 4. The method of claim 1, further comprising: in response tosending the first binding update message, receiving, by the userequipment from the home agent, a first binding acknowledgementacknowledging a binding registration.
 5. The method of claim 4, furthercomprising: in response to sending the second binding update message,receiving, by the user equipment from the home agent, a second bindingacknowledgement acknowledging another binding registration.
 6. Anapparatus comprising: a user equipment configured to send a firstbinding update message from the user equipment over the first accessnetwork to create a first binding cache entry at the home agent, whereinan identification of a first flow is included in (i) the first bindingupdate message and (ii) the first binding cache entry, the first accessnetwork being a home link, subsequent to sending the first bindingupdate message, send a second binding update message from the userequipment over the second access network to create a second bindingcache entry at the home agent, wherein an identification of a secondflow is included in (i) the second binding update message and (ii) thesecond binding cache entry, and in response to sending the secondbinding update message, send a third binding update message from theuser equipment over the first access network to modify the first bindingcache entry at the home agent, such that an identification of a thirdflow is included in (i) the third binding update message and (ii) themodified first binding cache entry, and such that a care-of address inthe modified first binding cache entry is set to a dummy value toindicate that the third flow is to be forwarded to the user equipmentvia the home link, and wherein the user equipment receives packets fromthe home agent through (i) the first access network based on themodified first binding cache entry, and (ii) the second access networkbased on the second binding cache entry.
 7. The apparatus of claim 6,wherein the first access network is a home link and the second accessnetwork is a foreign link.
 8. The apparatus of claim 6, wherein the userequipment uses a home address assigned to the user equipment as a sourceIP address of the first binding update message.
 9. The apparatus ofclaim 6, wherein the first binding cache entry uses a home addressassigned to the user equipment as a care-of address of the userequipment.
 10. The apparatus of claim 6, wherein the user equipment isfurther configured to: in response to sending the first binding updatemessage, receive, from the home agent, a first binding acknowledgementacknowledging a binding registration.
 11. The apparatus of claim 10,wherein the user equipment is further configured to: in response tosending the second binding update message, receive, from the home agent,a second binding acknowledgement acknowledging another bindingregistration.
 12. A method comprising: receiving, from a user equipment,a first binding update message over a first access network, the firstaccess network being a home link; in response to receiving the firstbinding update message, creating a first binding cache entry, whereinthe first binding cache entry includes identification of a first flow ofpackets; subsequent to receiving the first binding update message,receiving, from the user equipment, a second binding update message overa second access network; in response to receiving the second bindingupdate message, creating a second binding cache entry, wherein thesecond binding cache entry includes identification of a second flow ofpackets; subsequent to receiving the second binding update message,receiving, from the user equipment, a third binding update message overthe first access network; and in response to receiving the third bindingupdate message, modifying the first binding cache entry to generate amodified first binding cache entry, wherein the modified first bindingcache entry includes identification of a third flow of packets, suchthat a care-of address in the modified first binding cache entry is setto a dummy value to indicate that the third flow is to be forwarded tothe user equipment via the home link.
 13. The method of claim 12,further comprising: transmitting (i) packets through the first accessnetwork based on the modified first binding cache entry and (ii) packetsthrough the second access network based on the second binding cacheentry.
 14. The method of claim 12, wherein the user equipment uses ahome address assigned to the user equipment as a source IP address ofthe first binding update message.
 15. The method of claim 12, whereinthe first binding cache entry uses a home address assigned to the userequipment as a care-of address of the user equipment.
 16. The method ofclaim 12, further comprising: in response to creating the first bindingcache entry, transmitting a first binding acknowledgement.